dbcve.org
ZammadApplication

CVE-2021-42137

MEDIUM · 5.3 CVSS v3.1 Published 2021-10-11
Fix available
A fix is available. Upgrade to 5.0.1 or later.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
An issue was discovered in Zammad before 5.0.1. In some cases, there is improper enforcement of the privilege requirement for viewing a list of tickets that shows title, state, etc.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

Zammad before 5.0.1 contains a broken access control vulnerability where the system fails to properly enforce privilege requirements when displaying ticket lists. In certain cases, authenticated users can view ticket metadata (titles, states, etc.) for tickets they should not have permission to access, representing an Insecure Direct Object Reference (IDOR) or improper authorization issue.

MitigationUpgrade Zammad to version 5.0.1 or later to remediate this access control vulnerability. Verify that proper permission checks are enforced on all ticket listing endpoints after upgrading.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
ZammadApplication
Affected:< 5.0.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Determine Zammad version
    Access the Zammad admin interface and navigate to the About page or execute 'zammad --version' from the command line if you have server access. Alternatively, check the installed package version via your package manager (e.g., dpkg -l zammad or rpm -qi zammad).
    Affected if The installed version is below 5.0.1 (e.g., 5.0.0, 4.x.x, 3.x.x)
  2. Identify ticket access groups and permissions
    In the Zammad admin panel, review the Groups and Roles configuration under the Users and Rights section. Determine which roles have access to which ticket groups and whether any ticket groups have restricted access settings configured.
    Affected if Multiple roles or groups exist with different permission levels, and some tickets are restricted to specific groups or roles
  3. Test ticket metadata visibility with limited user account
    Create or use a test user account with restricted permissions (e.g., a user who should only see tickets in specific groups). Attempt to access the ticket list endpoint or UI and observe which ticket titles and metadata are visible in the overview. Compare against what that user should legitimately be able to see based on their assigned groups.
    Affected if The restricted user account can view ticket titles, states, or metadata for tickets outside their permitted groups or roles
  4. Check for ticket IDs in API or web responses
    If you have access to logs or can inspect API responses when a low-privilege user requests the ticket list, examine whether the response includes ticket entries with IDs or metadata for tickets the user should not have access to. Look for unexpected ticket titles or ticket IDs in the JSON or HTML response.
    Affected if API or web responses return ticket metadata for tickets outside the user's assigned permission scope

A user is affected if their Zammad installation is version 5.0.1 or higher and they have verified that ticket metadata is properly restricted based on user roles and groups.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.0.1 or later
Fixed in 5.0.1
Interim mitigation

Upgrade Zammad to version 5.0.1 or later to remediate this access control vulnerability. Verify that proper permission checks are enforced on all ticket listing endpoints after upgrading.

Recommended fix Moderate confidence

5.0.1

  1. 1. Backup your Zammad database and configuration files before upgrading
  2. 2. Upgrade Zammad to version 5.0.1 or later by following the official upgrade documentation for your installation method
  3. 3. After upgrade, verify the fix by testing that unauthorized users cannot view ticket lists they should not have access to
  4. 4. Confirm all users have appropriate role-based permissions configured

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Zammad Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,088.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-42137 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data